In a television ad unveiled Friday, Los Angeles Police Chief Charlie Beck suggests public safety in Los Angeles will suffer unless voters support Proposition A, a half-cent sales tax increase on the March 5 ballot.

The 30-second ad, paid for by a committee that has raised money largely from business interests, shows city paramedics loading a man into an ambulance and includes shots of firefighters in flashing trucks and ambulances responding to an emergency. A narrator with a deep voice intones the possible consequences of the measure's failure.

"Proposition A makes sure that 911 response times for our paramedics, firefighters and police are among the fastest in the nation. Without it, your safety is at risk,'' the voice-over says.

Beck then appears on-screen and makes the same pitch. "I’m Charlie Beck. Public safety is now in danger,'' he says. "Please support me by voting yes on Proposition A."

Opponents say the city can find other ways to reduce its deficit and that city revenues are starting to climb, making the tax hike unnecessary. They also argue that the money is needed to cover $167 million in raises being awarded to city workers between 2012 and 2014.

"It's just another attempt at extortion," said Jack Humphreville, who wrote the ballot argument against the tax.

The ad was created by Protect Los Angeles, a committee formed to support passage of the measure.

The group has raised more than $620,000, much of it from real estate developers and other interests doing business at City Hall. Records show that about one out of every $10 going to the committee has been provided by the outdoor advertising industry and its representatives.

Clear Channel Outdoor, which has been waging a public relations campaign to allow digital billboards to keep operating, gave $25,000 to the committee. Corona Outdoor Advertising gave $25,000; sign company Van Wagner donated $10,000.

"They’re all eager to get the council to approve something favorable to them on digital billboards,” said Dennis Hathaway, president of the Coalition to Ban Billboard Blight. “So there’s at least the appearance of a quid pro quo here.”

Harvey Englander, a campaign consultant, said the TV spot would begin appearing Monday on broadcast stations in the Los Angeles area. They are also sending direct mail appeals in the coming week, he said.

"It's going to be extensive,'' he said. "We're spending between $500,000 and $750,000 on media buys."

Prop. A would raise an estimated $200 million annually, money that city leaders say would be used to help close chronic budget shortfalls. About 70% of the city's budget goes to police and fire services.

The tax increase has the support of Mayor Antonio Villaraigosa, several council members, police and fire unions, and some business groups.

For the record, 7:30 p.m. Feb. 22: A previous version of this post incorrectly said the Proposition A campaign committee planned to purchase billboard advertising. The campaign has no such plans.